The broad objective of the proposed research is to correlate structure with function in biological membranes. Specifically, bacteriophage and phage ghosts will be used to introduce reproducible membrane perturbations under physiological conditions in E. coli. The target molecules of the perturbation will be the phospholipids. Membrane proteins are allotopic and therefore likely to undergo changes in function or activity when their lipid environment is altered. T4 ghost attachment to E. coli results in activation of host phospholipase. Ghost attachment also produces a number of functional changes in the membrane, including inhibition of active transport, macromolecular synthesis, lipid synthesis, efflux of cations and release of outer membrane components. The role of phospholipase catalyzed degradation of phospholipid in these ghost induced events will be evaluated, using E. coli mutants deficient in phospholipase. Two types of E. coli phospholipase A activity have been detected: a detergent sensitive (ds) activity, found in the cytoplasmic membrane, and a detergent resistant (dr) enzyme found in the outer memebrane. Mutants deficient in either or both will be used in the proposed research. Phage and ghost particles also contain a phospholipase activity. Its role in the changes in membrane function occurring immediately after phage and ghost attachment will be examined. Additionally, the involvement of both phage and host phospholipase in the lysis from within steps will be examined. Phage infection protects against activation of host phospholipase by superinfecting T4 ghosts. Additionally, phage do not cause immediate activation of host phospholipase unless protein synthesis is inhibited, suggesting the involvement of a phage gene specific product in phospholipase regulation. Extracts from phage infected cells will be examined for the presence of such an inhibitor.